First Good Headphones, Need Help!

For the past two months or so I have been researching headphones and still cannot figure out what to get. I am going to college and need Closed headphones so that I can be quiet when my roommate wants me to be. I'd like to stay under $300, and would like to avoid getting an amp if I do not have to. The headphones I have narrowed it down to are:

-ATH M50S

They seem to have a great reputation everywhere.

-AKG K271 MKii

Pretty good rep, seem really comfy. Like the features of removable cord / interchangeable pads - features do not exist on the newer K272 HD model

-Sennheiser HD 205

These haven't gotten much review, but I like the rotating arm better than swivel

-Panasonic (Technics?) RP DJ1200A

Same concept, like that rotating feature

-ATH ESW9A

Beautiful, but am worried about buying an authentic pair.

-Equation RP-21

Cheap but seem to have a good rep

What I am looking for is headphones that will sound good on all forms of music. I listen to a lot of techno / trance so I would like to have good bass, but I don't want it to dominate or destroy the other ranges. I also listen to a lot of classical music (I know, I'm weird), so I want that to sound really good on the same pair of headphones. The M50s and he K271 MKii's have the majority of my focus right now, because they both seem capable of doing this, but what do you guys think? Many people say that these represent almost all genre's well, but are slightly bass shy. Could I solve this with a relatively inexpensive amp, like the FiiO E5?

I would prefer circamaural over supra but as long as they are comfortable and ISOLATE well so that noise doesn't get out I don't really care.

Have tried Grado's and Sennheiser's and prefer the Sennheiser sound style over Grado to give you a feel of my preference, the Grado's all seemed (and these were the expensive models of both genre's including HD800 and GS1000i) painful to me on the higher notes (sibilance I believe?). Tried the Sony spread at the Sony store and didn't like any of their models. I have heard my friends ATH AD700's and thought they were nice but seriously lacked bass.

Open to other suggestions too, of course. Thank you so much for any help, and for reading my dilemma!

Hmmm. Nobody thinks the AKG are good? Also, I have been looking around and cannot really find a place, but do any of you know of any stores that carry any of these models? I'm in San Diego but am willing to go relatively far (even to LA) to try some of these).

Also the San Francisco meet thread was bumped recently. The last meet had a huge list of attendees sporting as many headphones as you could want to listen to. You might try to hit that up also if it's not too far.